U.S. patent application number 16/603059 was filed with the patent office on 2020-03-05 for pressure booster.
This patent application is currently assigned to SMC CORPORATION. The applicant listed for this patent is SMC CORPORATION. Invention is credited to Tsuyoshi ASABA, Tadashi IGARASHI, Ryosuke SATO.
Application Number | 20200072249 16/603059 |
Document ID | / |
Family ID | 61622648 |
Filed Date | 2020-03-05 |
United States Patent
Application |
20200072249 |
Kind Code |
A1 |
ASABA; Tsuyoshi ; et
al. |
March 5, 2020 |
PRESSURE BOOSTER
Abstract
A pressure booster is equipped with a pair of cylinders provided
on both sides of a center unit, pistons each disposed inside the
pair of cylinders, and a piston rod connecting the pistons. Each of
the cylinders has a drive chamber and a booster chamber partitioned
by the piston therein, and wherein the pressure booster is further
equipped with a switching valve that is switched by abutting on
each of the pistons, and a reset valve disposed in a fluid passage
connecting a supply port to one of the pair of drive chambers.
Inventors: |
ASABA; Tsuyoshi; (Abiko-shi,
JP) ; IGARASHI; Tadashi; (Koshigaya-shi, JP) ;
SATO; Ryosuke; (Tsukubamirai-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SMC CORPORATION |
Chiyoda-ku |
|
JP |
|
|
Assignee: |
SMC CORPORATION
Chiyoda-ku
JP
|
Family ID: |
61622648 |
Appl. No.: |
16/603059 |
Filed: |
February 26, 2018 |
PCT Filed: |
February 26, 2018 |
PCT NO: |
PCT/JP2018/006850 |
371 Date: |
October 4, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F15B 2211/30565
20130101; F15B 3/00 20130101; F15B 9/08 20130101; F15B 2211/85
20130101 |
International
Class: |
F15B 9/08 20060101
F15B009/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 7, 2017 |
JP |
2017-076416 |
Claims
1. A pressure booster comprising: a center unit; a pair of
cylinders provided on both sides of the center unit; pistons each
disposed inside the pair of cylinders; a piston rod connecting the
pair of pistons; a supply port supplied with pressure fluid; an
output port for outputting boosted pressure fluid; and an exhaust
port for discharging the pressure fluid; wherein the cylinders each
have a booster chamber and a drive chamber partitioned by the
piston; and wherein the pressure booster further comprises: a
switching valve that is switched by abutting on each of the pistons
to make one or the other of the pair of drive chambers communicate
with the supply port and to make the other or one of the pair of
drive chambers communicate with the exhaust port; and a reset valve
disposed in a fluid passage connecting the supply port and one of
the pair of drive chambers.
2. The pressure booster according to claim 1, wherein the switching
valve is incorporated into the center unit and includes: a pair of
push rods respectively abuttable on the pistons; and a spool slid
by the pair of push rods.
3. The pressure booster according to claim 1, wherein: the reset
valve is constructed as a normally closed valve switchable to a
communication state or a cutoff state between the supply port and
one of the pair of drive chambers and manually switchable to a
communication position.
4. The pressure booster according to claim 3, wherein: the reset
valve operates to be switched to the communication position when
receiving as a pilot pressure the fluid pressure in the drive
chamber.
5. The pressure booster according to claim 3, wherein: the reset
valve is incorporated into the center unit.
Description
TECHNICAL FIELD
[0001] The present invention relates to a pressure booster for
boosting and outputting a pressure fluid by the reciprocating
motion of pistons.
BACKGROUND ART
[0002] Heretofore, there is known a pressure booster equipped with
cylinders provided on opposite sides of a center unit, pistons
slidable in these cylinders, and a piston rod enabling the pistons
to reciprocate integrally. In this pressure booster, each cylinder
is partitioned by a piston into a booster chamber on an inner side
and a drive chamber on an outer side. When the piston on one side
is slid by the supply of compressed air from a switching valve to
the drive chamber on the one side, compressed air in the booster
chamber of the cylinder on the one side is boosted to be outputted.
Then, the switching valve is switched when the piston comes close
to a stroke end, and next, pressurized air is supplied to the drive
chamber of the cylinder on the other side, whereby the compressed
air in the boost chamber of the cylinder on the other side is
boosted to be outputted. By the repetition of this operation, it is
possible to boost and output the pressure fluid continuously.
[0003] In a field of a switching valve of a pressure booster, the
applicant of the present application has proposed a switching valve
made up from a main valve that is operated by air supplied to and
discharged from a pilot chamber for switching a driving compressed
air to a pair of drive chambers to output the driving compressed
air, and pilot valves that are operated by being pressed by the
pistons to supply or discharge air to the pilot chamber (see
Japanese Laid-Open Patent Publication No. 10-267002).
SUMMARY OF INVENTION
[0004] The present invention has been made in connection with the
aforementioned proposal, and it is an object of the present
invention to provide a pressure booster capable of being restarted
easily even when a switching valve is stopped at a neutral position
due to a drop in pressurized fluid supplied thereto or the
like.
[0005] A pressure booster according to the present invention
features comprising a center unit, a pair of cylinders provided on
both sides of the center unit, pistons each disposed insides the
pair of cylinders, a piston rod connecting the pair of pistons, a
supply port supplied with pressure fluid, an output port for
outputting boosted pressure fluid, and an exhaust port for
discharging the pressure fluid, wherein the cylinders each have a
booster chamber and a drive chamber partitioned by the piston, and
wherein the pressure booster further comprises a switching valve
that is switched by abutting on each of the pistons to make one or
the other of the pair of drive chambers communicate with the supply
port and to make the other or one of the pair of drive chambers
communicate with the exhaust port, and a reset valve disposed in a
fluid passage connecting the supply port and one of the pair of
drive chambers.
[0006] According to the pressure booster described above, it is
possible to be easily restarted even when the switching valve is
stopped at a neutral position due to a drop in pressurized fluid
supplied thereto or the like.
[0007] In the aforementioned pressure booster, it is preferable
that the switching valve is incorporated into the center unit and
is equipped with a pair of push rods being respectively abuttable
on the pistons and a spool slid by the pair of push rods. With this
construction, the switching valve becomes simple, operating
mechanically.
[0008] Further, it is preferable that the reset valve is
constituted as a normally closed valve which is switchable to a
communication state or a cutoff state between the supply port and
one of the pair of drive chambers and which is manually switchable
to a communication position. With this construction, it is possible
to manually restart the pressure booster reliably even when the
switching valve is stopped at the neutral position.
[0009] In this case, the reset valve may be one which operates to
be switched to the communication position when receiving as a pilot
pressure the fluid pressure in one of the drive chambers. With this
construction, even when the switching valve is stopped at the
neutral position, the switching valve is operated to restart the
pressure booster when the fluid pressure in one of the drive
chambers is higher than a predetermined value.
[0010] Furthermore, it is preferable that the reset valve is
incorporated into the center unit. With this construction, it is
possible to simplify a flow passage configuration employed for
disposition of the reset valve.
[0011] The pressure booster according to the present invention is
provided with the reset valve that is disposed in the flow passage
connecting the supply port to one of the pair of drive chambers and
is capable of being restarted easily even when the switching valve
is stopped at the neutral position due to a drop in fluid pressure
supplied thereto or the like.
[0012] The above and other objects, features and advantages of the
present invention will become more apparent from the following
description when taken in conjunction with the accompanying
drawings, in which preferred embodiments of the present invention
are shown by way of illustrative examples.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 is a front view of a pressure booster according to a
first embodiment of the present invention;
[0014] FIG. 2 is a right side view of the pressure booster shown in
FIG. 1;
[0015] FIG. 3 is a sectional view taken along the line III-III in
FIG. 2;
[0016] FIG. 4 is a sectional view taken along the line IV-IV in
FIG. 2;
[0017] FIG. 5 is a partially enlarged view of part of FIG. 3;
[0018] FIG. 6 is a schematic view in which the entire pressure
booster shown in FIG. 1 is illustrated with a circuit diagram;
and
[0019] FIG. 7 is a schematic view in which the entire pressure
booster according to a second embodiment of the present invention
is illustrated with a circuit diagram.
DESCRIPTION OF EMBODIMENTS
[0020] Hereafter, a pressure booster according to the present
invention will be described based on preferred embodiments with
reference to the accompanying drawings.
[0021] As shown in FIG. 1 to FIG. 4 and FIG. 6, reference numeral
10 denotes a pressure booster according to a first embodiment of
the present invention. The pressure booster 10 in the present
embodiment is arranged between a compressor (not shown) being a
supply source of pressure fluid (pressurized air, compressed air)
and an actuator (not shown) operated by boosted compressed air.
[0022] As shown in FIG. 3, the pressure booster 10 has a cylinder
mechanism including a pair of cylinder tubes (cylinders) 12a, 12b
and a pair of pistons 14a, 14b and also has a center unit 20 that
is provided between the pair of cylinder tubes 12a, 12b and
incorporates a regulating valve 16 and a switching valve 18.
[0023] The respective cylinder tubes 12a, 12b are formed in a
cylindrical shape and are closed at their opposite ends by end
plates 22a, 22b. The respective pistons 14a, 14b are movably
disposed inside the cylinder tubes 12a, 12b, and a piston packing
24 is fitted in an annular groove on an outer surface of each
piston 14a, 14b.
[0024] As shown in FIG. 4, the pair of pistons 14a, 14b is
integrally connected to each other by a piston rod 26. The center
unit 20 has a rod hole 28 at a central portion thereof. The rod
hole 28 penetrates the center unit 20 in an axial direction (the
arrow A-B direction), and the piston rod 26 that is movable is
inserted into the rod hole 28.
[0025] As shown in FIG. 3, inside the respective cylinder tubes
12a, 12b, cylinder chambers 30a, 30b are formed into which the
pistons 14a, 14b are inserted respectively. Fluid passages 32a, 32b
are respectively formed in parallel to the cylinder chambers 30a,
30b. The respective fluid passages 32a, 32b are formed separately
from the cylinder chambers 30a, 30b and communicate respectively
with the cylinder chambers 30a, 30b on end sides of the cylinder
tubes 12a, 12b where the end plates 22a, 22b are attached.
[0026] The respective cylinder chambers 30a, 30b are partitioned
into drive chambers 34, 34b and booster chambers 36a, 36b,
respectively. Each drive chamber 34a, 34b is provided between the
piston 14a, 14b and the end plate 22a, 22b, and pressure fluid is
supplied to or discharged from each drive chamber 34a, 34b. Each
booster chamber 36a, 36b is provided between the piston 14a, 14b
and the center unit 20 and operates to boost the pressure fluid.
The respective fluid passages 32a, 32b communicate with the drive
chambers 34a, 34b of the cylinder chambers 30a, 30b through first
passages 38a, 38b, respectively.
[0027] Outside the cylinder tubes 12a, 12b, a plurality of tie rods
40 is inserted from one end plate 22a to the other end plate 22b,
and end portions of the tie rods 40 protruding from the end plate
22b are tightened by nuts 42. Thus, the center unit 20 is held
between the cylinder tube 12a and the cylinder tube 12b. The center
unit 20 includes a center body 44 and a pair of side plates 46
attached to opposite ends of the axial direction (the arrow A-B
direction) of the center body 44.
[0028] The center body 44 has a supply port 45 supplied with
pressure fluid from the compressor, an output port 47 for
outputting boosted pressure fluid toward an actuator (not shown),
and an exhaust port 48 for discharging pressure fluid. The supply
port 45 is connected to a lead-in passage 50 that is in the center
body 44 communicating with the pair of booster chambers 36a, 36b
(refer to FIG. 4) and is also connected to a supply passage 52 that
is in the center body 44 communicating with either one of the pair
of the fluid passages 32a, 32b through the switching valve 18
(refer to FIG. 3). The supply passage 52 is provided with the
regulating valve 16 to which the pressure at the output port 47 is
fed back, so that the flow rate of the pressure fluid can be
regulated when a handle 54 provided on an upper portion of the
center body 44 is rotated by the worker.
[0029] As shown in FIG. 4, between the lead-in passage 50 and the
respective booster chambers 36a, 36b, there are provided first
check valves 56a, 56b for allowing fluid flow from the lead-in
passage 50 toward the booster chambers 36a, 36b but blocking fluid
flow from the booster chambers 36a, 36b toward the lead-in passage
50. The output port 47 is connected to a lead-out passage 58 that
is in the center body 44 communicating with the pair of booster
chambers 36a, 36b. Between the lead-out passage 58 and the
respective booster chambers 36a, 36b, there are provided second
check valves 60a, 60b for allowing fluid flow from the booster
chambers 36a, 36b toward the lead-out passage 58 but blocking fluid
flow from the lead-out passage 58 toward the booster chambers 36a,
36b. The first check valves 56a, 56b and the second check valves
60a, 60b are incorporated into the center body 44 by the use of the
side plates 46.
[0030] As shown in FIG. 5, the switching valve 18 is equipped with
a valve body assembly 62 incorporated into the center body 44 by
the use of the side plates 46, a spool 64 slidable in the valve
body assembly 62, and a pair of push rods 66a, 66b protruding
respectively into the respective booster chambers 36a, 36b. The
valve body assembly 62 includes a cylindrical sleeve 68 and a pair
of side valve bodies 70 arranged on both sides of the sleeve
68.
[0031] The sleeve 68 is provided with an inlet port 72 at a central
portion of the axial direction (the arrow A-B direction) and is
provided on both sides of the inlet port 72 with a pair of outlet
ports 76a, 76b apart from the inlet port 72 in the axial direction.
The inlet port 72 is connected to the supply passage 52, and the
respective outlet ports 76a, 76b are connected to the fluid
passages 32a, 32b through the second passages 74a, 74b,
respectively. Further, the side valve bodies 70, 70 are
respectively provided therein with a pair of exhaust passages 78
connected to the exhaust port 48. Between the center body 44 and
the valve body assembly 62, sealing members 80 are provided for an
airtight sealing between the inlet port 72, the outlet ports 76a,
76b, and the exhaust passages 78.
[0032] The spool 64 is formed in a cylindrical shape and is
provided at its outer periphery with a first land portion 82 and a
second land portion 84 slidably contacting with an inner peripheral
surface of the sleeve 68. When the spool 64 is slid toward the
right (the arrow A direction) inside the valve body assembly 62,
the first land portion 82 is positioned between the outlet port 76b
on the left side and the inlet port 72, while the second land
portion 84 is positioned between the outlet port 76a on the right
side and the exhaust passage 78 on the right side. Hereafter, this
state is regarded as the spool 64 or the switching valve 18 being
located at a "first position" (refer to FIG. 6). When the spool 64
is slid toward the left (in the arrow B direction) inside the valve
body assembly 62, the first land portion 82 is positioned between
the exhaust passage 78 on the left side and the outlet port 76b on
the left side, while the second land portion 84 is positioned
between the inlet port 72 and the outlet port 76a on the right
side. Hereafter, this state is regarded as the spool 64 or the
switching valve 18 being at a "second position". In this way, it is
possible to switch the supply passage 52 and the exhaust passages
78 with respect to the pair of the outlet ports 76a, 76b.
[0033] The respective push rods 66a, 66b are movably inserted
through insertion holes which penetrates central portions of the
side valve bodies 70 in the axial direction (the arrow A-B
direction), and sealing members 86 are provided between the push
rods 66a, 66b and the side valve bodies 70. The respective push
rods 66a, 66b are, at end portions that protrude on the booster
chamber 36a, 36b sides, abuttable on the pistons 14a, 14b.
[0034] The spool 64 is provided at its inner peripheral surface
with a small-diameter portion 88 that protrudes radially inward and
extends over a predetermined length in the axial direction. Thus,
the spool 64 is provided at its inner peripheral surface with a
pair of step portions 90. Mutually facing end portions of the pair
of push rods 66a, 66b are inserted into the spool 64, and
respective push rods 66a, 66b are engageable with the step portions
90 of the spool 64 at first flange portions 92 formed at the end
portions, respectively. The respective push rods 66a, 66b are
provided with second flange portions 94 at portions close to
central portions of the axial directions and are restrained from
moving toward the booster chamber 36a, 36b sides of the push rods
66a, 66b due to the abutment of the second flange portions 94 on
the side valve bodies 70, respectively. A return spring 96 is
provided between mutually facing end portions of the pair of push
rods 66a, 66b.
[0035] As shown in FIG. 3, a reset valve 98 including a valve body
100 and a reset button 102 is attached to the center body 44. The
reset valve 98 is constituted as a normally closed valve that is
switchable to a communication state or a cutoff state between a
third passage 106 connected to the supply passage 52 and the second
passage 74a connected to the fluid passage 32a. The valve body 100
receives an urging force of a spring 104, so that usually, the
reset valve 98 stays at a cutoff position. When the worker pushes
the reset button 102, the valve body 100 is pushed by the reset
button 102 to be moved against the urging fore of the spring 104.
Thus, the third passage 106 is brought into communication with the
second passage 74a, whereby the pressure fluid from the compressor
is directly introduced into the drive chamber 34a.
[0036] The pressure booster 10 according to the first embodiment of
the present invention is basically constructed as described above.
Next, the operation and operational effects will be described.
Incidentally, an initial position is assumed to be the state that
as shown in FIG. 6, the switching valve 18 is at the first position
and that the piston 14a has been moved to the end plate 22a side
(in the arrow A direction).
[0037] At this initial position, the second land portion 84 of the
spool 64 is located between the outlet port 76a on the right side
and the exhaust passage 78 on the right side, and the outlet port
76a on the right side is in communication with the inlet port 72.
That is, the fluid passage 32a is connected to the supply passage
52 through the second passage 74a. Further, the first land portion
82 of the spool 64 is located between the outlet port 76b on the
left side and the inlet port 72, and the outlet port 76b on the
left side is in communication with the exhaust passage 78 on the
left side. That is, the fluid passage 32b on the other side is
connected to the exhaust passage 78 through the second passage
74b.
[0038] At this initial position, pressure fluid is supplied from
the compressor (not shown) to the supply port 45, and thus, the
pressure fluid flows into the lead-in passage 50 and is led to the
booster chambers 36a, 36b respectively through the first check
valves 56a, 56b.
[0039] Part of the pressure fluid supplied from the supply port 45
is regulated in flow rate by the regulating valve 16 and flows to
the switching valve 18 through the supply passage 52. Then, the
pressure fluid is supplied to the fluid passage 32a through the
switching valve 18 held at the first position and is further
supplied to the drive chamber 34a.
[0040] The pressure fluid led to the drive chamber 34a presses the
piston 14a toward the center unit 20 side (in the arrow B
direction), and thus, the pressure fluid in the booster chamber 36a
is boosted by the piston 14a. The pressure fluid thus boosted is
led through the second check valve 60a and is outputted by being
led from the lead-out passage 58 to the output port 47.
[0041] On the other hand, the sliding of the piston 14b moved
integrally with the piston 14a makes the volume of the drive
chamber 34b smaller, and thus, the pressure fluid in the drive
chamber 34b is led to the exhaust passage 78 through the fluid
passage 32b and the switching valve 18 being at the first position
and is discharged from the exhaust port 48.
[0042] Then, when moved toward the center unit 20 side (in the
arrow B direction) up to the end position, the piston 14a abuts on
the push rod 66a of the switching valve 18 to press the push rod
66a. As a result, the push rod 66a is engaged with the spool 64 at
the first flange portion 92 and moves the spool 64 to the second
position. That is, the switching valve 18 is switched to the second
position.
[0043] This time, the pressure fluid supplied to the supply passage
52 is supplied to the fluid passage 32b and the drive chamber 34b
through the switching valve 18 being at the second position, and
thus, the piston 14b is moved toward the center unit 20 side (in
the arrow A direction). Thus, the pressure fluid in the booster
chamber 36b is boosted, and the pressure fluid thus boosted goes
through the second check valve 60b and is outputted from the output
port 47. When moved toward the center unit 20 side (in the arrow A
direction) up to the end position, the piston 14b presses the push
rod 66b. This results in switching the switching valve 18 again to
the first position, whereby the pressure fluid is supplied to the
drive chamber 34a. In the same manner as described above, the
piston 14a and the piston 14b integrally repeat the reciprocating
motion, whereby the boosted pressure fluid is continuously
outputted from the output port 47.
[0044] Here, it may be the case that the thrust or driving force of
the pistons 14a, 14b becomes insufficient due to the pressure of
the pressure fluid supplied being low, the pressure difference
being small between the booster chambers 36a, 36b and the drive
chambers 34a, 34b, or a back pressure exerted on the exhaust port
48. Further, the sliding resistance of the pistons 14a, 14b or the
switching valve 18 may become large.
[0045] In the case like this, the spool 64 may remain stopped at an
intermediate position between the first position and the second
position. In this state, it is assumed that the first land portion
82 is at a position overlapping with the outlet port 76b on the
left side and hence that an imperfect cutoff state has arisen
between the inlet port 72 and the outlet port 76b on the left side
and between the outlet port 76b on the left side and the exhaust
passage 78 on the left side. Likewise, it is assumed that the
second land portion 84 is at a position overlapping with the outlet
port 76a on the right side and hence that an imperfect cutoff state
has arisen between the inlet port 72 and the outlet port 76a on the
right side and between the outlet port 76a on the right side and
the exhaust passage 78 on the right side.
[0046] When the worker pushes the reset button 102 in the
aforementioned state, the pressure fluid from the compressor is
introduced directly to the drive chamber 34a. As a result, the
piston 14a is pressed toward the center unit 20 side, whereby the
pressure booster 10 is restarted.
[0047] According to the pressure booster 10 of the present
embodiment, the manually operable reset valve 98 is disposed in a
passage connecting the supply port 45 and the drive chamber 34a,
and thus, the restarting can easily be made even when the switching
valve 18 is stopped at the neutral position due to a drop in the
fluid pressure supplied thereto or the like.
[0048] Next, with reference to FIG. 7, description will be made
regarding a pressure booster 110 according to a second embodiment
of the present invention. The pressure booster 110 has a reset
valve 112 which differs in construction from the reset valve 98 of
the first embodiment. Incidentally, the same components as those of
the pressure booster 10 according to the first embodiment are given
the same reference numerals and will be omitted from being
described in detail.
[0049] The reset valve 112 is constructed as a normally closed
valve which is switchable to a communication state or a cutoff
state between the supply passage 52 and the fluid passage 32a, and
the fluid pressure in the fluid passage 32a acts as a pilot
pressure. That is, the reset valve 112 operates to be switched to a
communication position when the fluid pressure in the fluid passage
32a is higher than a predetermined value.
[0050] Further, the pushing by the worker of a reset button 102
enables the supply passage 52 to communicate with the fluid passage
32a, so that it also becomes possible to directly introduce the
pressure fluid from the compressor to the drive chamber 34a.
[0051] According to the pressure booster 110 of this second
embodiment, the reset valve 112 operates to be switched to the
communication position by receiving as the pilot pressure the fluid
pressure in the drive chamber 34a. Therefore, even when the
switching valve 18 is stopped at the neural position, the switching
valve 18 operates when the fluid pressure in the drive chamber 34a
is higher than the predetermined value, so that the pressure
booster 110 is restarted.
[0052] The pressure booster according to the present invention is
not limited to the foregoing embodiments. It is needless to say
that the present invention can take various constructions without
departing from the gist of the present invention.
* * * * *